Khabib Nurmagomedov entered the UFC a perfect 16-0 and has not lost since. In 2012, Nurmagomedov (28-0 MMA, 12-0 UFC) faced wrestler Kamal Shalorus, who was 16 years his senior.
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UFC free fight: Relive Khabib Nurmagomedov’s UFC debut in 2012 – MMA Junkie